groff_char(7) Miscellaneous Information Manual groff_char(7)
Name
groff_char - GNU roff special character and glyph repertoire
Description
The GNU roff typesetting system has a large glyph repertoire suitable
for production of varied literary, professional, technical, and
mathematical documents. groff works with characters; an output device
renders glyphs. groff's input character set is restricted to that
defined by the standards ISO Latin-1 (ISO 8859-1) and CCSID "code page"
1047 (an EBCDIC arrangement of Latin-1). For ease of document
maintenance in UTF-8 environments, it is advisable to use only the
Unicode basic Latin code points, a subset of all of the foregoing
historically referred to as US-ASCII, which has only 94 visible,
printable code points. In groff, these are termed ordinary characters.
Often, many more are desired in output.
AT&T troff in the 1970s faced a similar problem: the available
typesetter's glyph repertoire differed from that of the computers that
controlled it. troff's solution was a form of escape sequence known as
a special character to access several dozen additional glyphs available
in the fonts prepared for mounting in the phototypesetter. These
glyphs were mapped onto a two-character name space for a degree of
mnemonic convenience; for example, the escape sequence \(aa encoded an
acute accent and \(sc a section sign.
groff has lifted historical roff limitations on special character name
lengths, but recognizes and retains compatibility with the historical
names. groff expands the lexicon of glyphs available by name and
permits users to define their own special character escape sequences
with the char request. Special character names are groff identifiers;
see section "Identifiers" in groff(7). Our discussion uses the terms
"glyph name" and "special character name" interchangeably; we assume no
character translations or redefinitions.
This document lists all of the glyph names predefined by groff's font
description files and presents the systematic notation by which it
enables access to arbitrary Unicode code points and construction of
composite glyphs. Glyphs listed may be unavailable, or may vary in
appearance, depending on the output device and font chosen when the
page was formatted. This page was rendered for device ascii using font
0.
A few escape sequences that are not groff special characters also
produce glyphs; these exist for syntactical or historical reasons. \',
\`, \-, and \_ are translated on input to the special character escape
sequences \[aa], \[ga], \[-], and \[ul], respectively. Others include
\\, \. (backslash-dot), and \e; see groff(7). A small number of
special characters represent glyphs that are not encoded in Unicode;
examples include the baseline rule \[ru] and the Bell System logo
\[bs].
In groff, you can test output device support for any character
(ordinary or special) with the conditional expression operator "c".
.ie c \[bs] \{Welcome to the \[bs] Bell System;
did you get the Wehrmacht helmet or the Death Star?\}
.el No Bell System logo.
For brevity in the remainder of this document, we shall refer to
systems conforming to the ISO 646:1991 IRV, ISO 8859, or ISO 10646
("Unicode") character encoding standards as "ISO" systems, and those
employing IBM code page 1047 as "EBCDIC" systems. That said, EBCDIC
systems that support groff are known to also support UTF-8.
While groff accepts eight-bit encoded input, not all such code points
are valid as input. On ISO platforms, character codes 0, 11, 13-31,
and 128-159 are invalid. (This is all C0 and C1 controls except for
SOH through LF [Control+A to Control+J], and FF [Control+L].) On
EBCDIC platforms, 0, 8-9, 11, 13-20, 23-31, and 48-63 are invalid.
Some of these code points are used by groff for internal purposes,
which is one reason it does not support UTF-8 natively.
Fundamental character set
The ordinary characters catalogued above, plus the space, tab, newline,
and leader (Control+A), form the fundamental character set for groff
input; anything in the language, even over one million code points in
Unicode, can be expressed using it. On ISO systems, code points in the
range 33-126 comprise a common set of printable glyphs in all of the
aforementioned ISO character encoding standards. It is this character
set and (with some noteworthy exceptions) the corresponding glyph
repertoire for which AT&T troff was implemented. On EBCDIC systems,
printable characters are in the range 66-201 and 203-254; those without
counterparts in the ISO range 33-126 are discussed in the next
subsection.
All of the following characters map to glyphs as you would expect.
+----------------------------------------------------------+
|! # $ % & ( ) * + , . / 0 1 2 3 4 5 6 7 8 9 : ; < = > ? @ |
|A B C D E F G H I J K L M N O P Q R S T U V W X Y Z [ ] _ |
|a b c d e f g h i j k l m n o p q r s t u v w x y z { | } |
+----------------------------------------------------------+
The remaining ordinary characters surprise computing professionals and
others intimately familiar with the ISO character encodings. The
developers of AT&T troff chose mappings for them that would be useful
for typesetting technical literature in a broad range of scientific
disciplines: Bell Labs used the system for preparation of AT&T's patent
filings with the U.S. government. Further, the prevailing character
encoding standard in the 1970s, USAS X3.4-1968 ("ASCII"), deliberately
supported semantic ambiguity at some code points, and outright
substitution at several others, to suit the localization demands of
various national standards bodies.
The table below presents the seven exceptional code points with their
typical keycap engravings, their glyph mappings and semantics in roff
systems, and the escape sequences producing the Unicode basic Latin
character they replace. The first, the neutral double quote, is a
partial exception because it does represent itself, but since the roff
language also uses it to quote macro arguments, groff supports a
special character escape sequence as an alternative form so that the
glyph can be easily included in macro arguments without requiring the
user to master the quoting rules that AT&T troff required in that
context. (Some requests, like ds, also treat " non-literally.)
Furthermore, not all of the special character escape sequences are
portable to AT&T troff and all of its descendants; these groff
extensions are presented using its special character form \[], whereas
portable special character escape sequences are shown in the
traditional \( form. \- and \e are portable to all known troffs. \e
means "the glyph of the current escape character"; it therefore can
produce unexpected output if the ec request is used. On devices with a
limited glyph repertoire, glyphs in the "keycap" and "appearance"
columns on the same row of the table may look identical; except for the
neutral double quote, this will not be the case on more-capable
devices. Review your document using as many different output devices
as possible.
+-------------------------------------------------------------------+
|Keycap Appearance and meaning Special character and meaning |
+-------------------------------------------------------------------+
|" " neutral double quote \[dq] neutral double quote |
|' ' closing single quote \[aq] neutral apostrophe |
|- - hyphen \- or \[-] minus sign/Unix dash |
|\ (escape character) \e or \[rs] reverse solidus |
|^ <?> modifier circumflex \(ha circumflex/caret/"hat" |
|` ` opening single quote \(ga grave accent |
|~ ~ modifier tilde \(ti tilde |
+-------------------------------------------------------------------+
The hyphen-minus is a particularly unfortunate case of overloading.
Its awkward name in ISO 8859 and later standards reflects the many
distinguishable purposes to which it had already been put by the 1980s,
including a hyphen, a minus sign, and (alone or in repetition) dashes
of varying widths. For best results in roff systems, use the "-"
character in input outside an escape sequence only to mean a hyphen, as
in the phrase "long-term". For a minus sign in running text or a Unix
command-line option dash, use \- (or \[-] in groff if you find it helps
the clarity of the source document). (Another minus sign, for use in
mathematical equations, is available as \[mi]). AT&T troff supported
em-dashes as \(em, as does groff.
The special character escape sequence for the apostrophe as a neutral
single quote is typically needed only in technical content; typing
words like "can't" and "Anne's" in a natural way will render correctly,
because in ordinary prose an apostrophe is typeset either as a closing
single quotation mark or as a neutral single quote, depending on the
capabilities of the output device. By contrast, special character
escape sequences should be used for quotation marks unless portability
to limited or historical troff implementations is necessary; on those
systems, the input convention is to pair the grave accent with the
apostrophe for single quotes, and to double both characters for double
quotes. AT&T troff defined no special characters for quotation marks
or the apostrophe. Repeated single quotes (``thus'') will be visually
distinguishable from double quotes ("thus") on terminal devices, and
perhaps on others (depending on the font selected).
+----------------------------------------------------------------+
|AT&T troff input recommended groff input |
+----------------------------------------------------------------+
|A Winter's Tale A Winter's Tale |
|`U.K. outer quotes' \[oq]U.K. outer quotes\[cq] |
|`U.K. ``inner'' quotes' \[oq]U.K. \[lq]inner\[rq] quotes\[cq] |
|``U.S. outer quotes'' \[lq]U.S. outer quotes\[rq] |
|``U.S. `inner' quotes'' \[lq]U.S. \[oq]inner\[cq] quotes\[rq] |
+----------------------------------------------------------------+
If you frequently require quotation marks in your document, see if the
macro package you're using supplies strings or macros to facilitate
quotation, or define them yourself (except in man pages).
Using Unicode basic Latin characters to compose boxes and lines is ill-
advised. roff systems have special characters for drawing horizontal
and vertical lines; see subsection "Rules and lines" below.
Preprocessors like tbl(1) and pic(1) draw boxes and will produce the
best possible output for the device, falling back to basic Latin glyphs
only when necessary.
Eight-bit encodings and Latin-1 supplement
ISO 646 is a seven-bit code encoding 128 code points; eight-bit codes
are twice the size. ISO 8859-1 and code page 1047 allocated the
additional space to what Unicode calls "C1 controls" (control
characters) and the "Latin-1 supplement". The C1 controls are neither
printable nor usable as groff input.
Two Latin-1 supplement characters are handled specially on input.
troff never produces them as output.
NBSP encodes a no-break space; it is mapped to \~, the adjustable
non-breaking space escape sequence.
SHY encodes a soft hyphen; it is mapped to \%, the hyphenation
control escape sequence.
The remaining characters in the Latin-1 supplement represent
themselves. Although they can be specified directly with the keyboard
on systems configured to use Latin-1 as the character encoding, it is
more portable, both to other roff systems and to UTF-8 environments, to
use their special character escape sequences, shown below. The glyph
descriptions we use are non-standard in some cases, for brevity.
! \[r!] inverted exclamation mark N \[~N] N tilde
c \[ct] cent sign O \[`O] O grave
L \[Po] pound sign O \['O] O acute
x \[Cs] currency sign O \[^O] O circumflex
Y \[Ye] yen sign O \[~O] O tilde
| \[bb] broken bar O \[:O] O dieresis
<section> \[sc] section sign x \[mu] multiplication sign
" \[ad] dieresis accent O \[/O] O slash
(C) \[co] copyright sign U \[`U] U grave
a \[Of] feminine ordinal indicator U \['U] U acute
<< \[Fo] left double chevron U \[^U] U circumflex
~ \[no] logical not U \[:U] U dieresis
(R) \[rg] registered sign Y \['Y] Y acute
- \[a-] macron accent Th \[TP] uppercase thorn
<degree> \[de] degree sign ss \[ss] lowercase sharp s
+- \[+-] plus-minus a \[`a] a grave
^2 \[S2] superscript two a \['a] a acute
^3 \[S3] superscript three a \[^a] a circumflex
' \[aa] acute accent a \[~a] a tilde
<micro> \[mc] micro sign a \[:a] a dieresis
<paragraph> \[ps] pilcrow sign a \[oa] a ring
. \[pc] centered period ae \[ae] ae ligature
, \[ac] cedilla accent c \[,c] c cedilla
^1 \[S1] superscript one e \[`e] e grave
o \[Om] masculine ordinal indicator e \['e] e acute
>> \[Fc] right double chevron e \[^e] e circumflex
1/4 \[14] one quarter symbol e \[:e] e dieresis
1/2 \[12] one half symbol i \[`i] i grave
3/4 \[34] three quarters symbol i \['i] e acute
? \[r?] inverted question mark i \[^i] i circumflex
A \[`A] A grave i \[:i] i dieresis
A \['A] A acute dh \[Sd] lowercase eth
A \[^A] A circumflex n \[~n] n tilde
A \[~A] A tilde o \[`o] o grave
A \[:A] A dieresis o \['o] o acute
A \[oA] A ring o \[^o] o circumflex
AE \[AE] AE ligature o \[~o] o tilde
C \[,C] C cedilla o \[:o] o dieresis
E \[`E] E grave / \[di] division sign
E \['E] E acute o \[/o] o slash
E \[^E] E circumflex u \[`u] u grave
E \[:E] E dieresis u \['u] u acute
I \[`I] I grave u \[^u] u circumflex
I \['I] I acute u \[:u] u dieresis
I \[^I] I circumflex y \['y] y acute
I \[:I] I dieresis th \[Tp] lowercase thorn
Dh \[-D] uppercase eth y \[:y] y dieresis
Special character escape forms
Glyphs that lack a character code in the basic Latin repertoire to
directly represent them are entered by one of several special character
escape forms. Such glyphs can be simple or composite, and accessed
either by name or numerically by code point. Code points and combining
properties are determined by character encoding standards, whereas
glyph names as used here originated in AT&T troff special character
escape sequences. Predefined glyph names use only characters in the
basic Latin repertoire.
\(gl is a special character escape sequence for the glyph with the
two-character name gl. This is the original syntax form
supported by AT&T troff. The acute accent, \(aa, is an example.
\C'glyph-name'
is a special character escape sequence for glyph-name, which can
be of arbitrary length. The delimiter, shown here as a neutral
apostrophe, can be any character not occurring in glyph-name.
This syntax form was introduced in later versions of AT&T
device-independent troff. The foregoing acute accent example
can be expressed as \C'aa'.
\[glyph-name]
is a special character escape sequence for glyph-name, which can
be of arbitrary length but must not contain a closing square
bracket "]". (No glyph names predefined by groff employ "]".)
The foregoing acute accent example can be expressed in groff as
\[aa].
\C'c' and \[c] are not synonyms for the ordinary character "c", but
request the special character named "\c". For example, "\[a]" is not
"a", but rather a special character with the internal glyph name (used
in font description files and diagnostic messages) \a, which is
typically undefined. The only such glyph name groff predefines is the
minus sign, which can therefore be accessed as \C'-' or \[-].
\[base-char composite-1 composite-2 ... composite-n]
is a composite glyph. Glyphs like a lowercase "e" with an acute
accent, as in the word "caf", can be expressed as \[e aa]. See
subsection "Accents" below for a table of combining glyph names.
Unicode encodes far more characters than groff has glyph names for;
special character escape forms based on numerical code points enable
access to any of them. Frequently used glyphs or glyph combinations
can be stored in strings, and new glyph names can be created ad hoc
with the char request; see groff(7).
\[unnnn[n[n]]]
is a Unicode numeric special character escape sequence. Any
Unicode code point can be accessed with four to six hexadecimal
digits, with hexadecimal letters accepted in uppercase form
only. Thus, \[u02DA] accesses the (spacing) ring accent,
producing "o".
Unicode code points can be composed as well; when they are, GNU troff
requires NFD (Normalization Form D), where all Unicode glyphs are
maximally decomposed. (Exception: precomposed characters in the
Latin-1 supplement described above are also accepted. Do not count on
this exception remaining in a future GNU troff that accepts UTF-8 input
directly.) Thus, GNU troff accepts "caf\['e]", "caf\[e aa]", and
"caf\[u0065_0301]", as ways to input "cafe". (Due to its legacy 8-bit
encoding compatibility, at present it also accepts "caf\[u00E9]" on ISO
Latin-1 systems.)
\[ubase-char[_combining-component]...]
constructs a composite glyph from Unicode numeric special
character escape sequences. The code points of the base glyph
and the combining components are each expressed in hexadecimal,
with an underscore (_) separating each component. Thus,
\[u006E_0303] produces "".
\[charnnn]
expresses an eight-bit code point where nnn is the code point of
the character, a decimal number between 0 and 255 without
leading zeroes. This legacy numeric special character escape
sequence is used to map characters onto glyphs via the trin
request in macro files loaded by grotty(1).
Glyph tables
In this section, groff's glyph name repertoire is presented in tabular
form. The meanings of the columns are as follows.
Output shows the glyph as it appears on the device used to render this
document; although it can have a notably different shape on
other devices (and is subject to user-directed translation and
replacement), groff attempts reasonable equivalency on all
output devices.
Input shows the groff character (ordinary or special) that normally
produces the glyph. Some code points have multiple glyph
names.
Unicode is the code point notation for the glyph or combining glyph
sequence as described in subsection "Special character escape
forms" above. It corresponds to the standard notation for
Unicode short identifiers such that groff's unnnn is equivalent
to Unicode's U+nnnn.
Notes describes the glyph, elucidating the mnemonic value of the
glyph name where possible.
A plus sign "+" indicates that the glyph name appears in the
AT&T troff user's manual, CSTR #54 (1992 revision). When using
the AT&T special character syntax \(xx, widespread portability
can be expected from such names.
Entries marked with "***" denote glyphs used for mathematical
purposes. On typesetting devices, such glyphs are typically
drawn from a special font (see groff_font(5)). Often, such
glyphs lack bold or italic style forms or have metrics that
look incongruous in ordinary prose. A few which are not
uncommon in running text have "text variants", which should
work better in that context. Conversely, a handful of glyphs
that are normally drawn from a text font may be required in
mathematical equations. Both sets of exceptions are noted in
the tables where they appear ("Logical symbols" and
"Mathematical symbols").
Basic Latin
Apart from basic Latin characters with special mappings, described in
subsection "Fundamental character set" above, a few others in that
range have special character glyph names. These were defined for ease
of input on non-U.S. keyboards lacking keycaps for them, or for
symmetry with other special character glyph names serving a similar
purpose.
The vertical bar is overloaded; the \[ba] and \[or] escape sequences
may render differently. See subsection "Mathematical symbols" below
for special variants of the plus, minus, and equals signs normally
drawn from this range.
Output Input Unicode Notes
------------------------------------------------------------------------
" \[dq] u0022 neutral double quote
# \[sh] u0023 number sign
$ \[Do] u0024 dollar sign
' \[aq] u0027 apostrophe, neutral single quote
/ \[sl] u002F slash, solidus +
@ \[at] u0040 at sign
[ \[lB] u005B left square bracket
\ \[rs] u005C reverse solidus
] \[rB] u005D right square bracket
^ \[ha] u005E circumflex, caret, "hat"
{ \[lC] u007B left brace
| | u007C bar
| \[ba] u007C bar
| \[or] u007C bitwise or +
} \[rC] u007D right brace
~ \[ti] u007E tilde
Supplementary Latin letters
Historically, \[ss] could be considered a ligature of "sz". An
uppercase form is available as \[u1E9E], but in the German language it
is of specialized use; ss does not normally uppercase-transform to it,
but rather to "SS". "Lowercase f with hook" is also used as a function
symbol; see subsection "Mathematical symbols" below.
Output Input Unicode Notes
------------------------------------------------------------------------
Dh \[-D] u00D0 uppercase eth
dh \[Sd] u00F0 lowercase eth
Th \[TP] u00DE uppercase thorn
th \[Tp] u00FE lowercase thorn
ss \[ss] u00DF lowercase sharp s
i \[.i] u0131 i without tittle
j \[.j] u0237 j without tittle
f \[Fn] u0192 lowercase f with hook, function
L \[/L] u0141 L with stroke
l \[/l] u0142 l with stroke
O \[/O] u00D8 O with stroke
o \[/o] u00F8 o with stroke
Ligatures and digraphs
Output Input Unicode Notes
------------------------------------------------------------------------
ff \[ff] u0066_0066 ff ligature +
fi \[fi] u0066_0069 fi ligature +
fl \[fl] u0066_006C fl ligature +
ffi \[Fi] u0066_0066_0069 ffi ligature +
ffl \[Fl] u0066_0066_006C ffl ligature +
AE \[AE] u00C6 AE ligature
ae \[ae] u00E6 ae ligature
OE \[OE] u0152 OE ligature
oe \[oe] u0153 oe ligature
IJ \[IJ] u0132 IJ digraph
ij \[ij] u0133 ij digraph
Accents
Normally, the formatting of a special character advances the drawing
position as an ordinary character does. groff's composite request
designates a special character as combining. The composite.tmac macro
file, loaded automatically by the default troffrc, maps the following
special characters to the combining characters shown below. The non-
combining code point in parentheses is used when the special character
occurs in isolation (compare "caf\[e aa]" and "caf\[aa]e").
Output Input Unicode Notes
------------------------------------------------------------------------
" \[a"] u030B (u02DD) double acute accent
- \[a-] u0304 (u00AF) macron accent
. \[a.] u0307 (u02D9) dot accent
^ \[a^] u0302 (u005E) circumflex accent
' \[aa] u0301 (u00B4) acute accent +
` \[ga] u0300 (u0060) grave accent +
` \[ab] u0306 (u02D8) breve accent
, \[ac] u0327 (u00B8) cedilla accent
" \[ad] u0308 (u00A8) dieresis accent
v \[ah] u030C (u02C7) caron accent
o \[ao] u030A (u02DA) ring accent
~ \[a~] u0303 (u007E) tilde accent
, \[ho] u0328 (u02DB) hook accent
Accented characters
All of these glyphs can be composed using combining glyph names as
described in subsection "Special character escape forms" above; the
names below are short aliases for convenience.
Output Input Unicode Notes
------------------------------------------------------------------------
A \['A] u0041_0301 A acute
\['C] u0043_0301 C acute
E \['E] u0045_0301 E acute
I \['I] u0049_0301 I acute
O \['O] u004F_0301 O acute
U \['U] u0055_0301 U acute
Y \['Y] u0059_0301 Y acute
a \['a] u0061_0301 a acute
\['c] u0063_0301 c acute
e \['e] u0065_0301 e acute
i \['i] u0069_0301 i acute
o \['o] u006F_0301 o acute
u \['u] u0075_0301 u acute
y \['y] u0079_0301 y acute
A \[:A] u0041_0308 A dieresis
E \[:E] u0045_0308 E dieresis
I \[:I] u0049_0308 I dieresis
O \[:O] u004F_0308 O dieresis
U \[:U] u0055_0308 U dieresis
\[:Y] u0059_0308 Y dieresis
a \[:a] u0061_0308 a dieresis
e \[:e] u0065_0308 e dieresis
i \[:i] u0069_0308 i dieresis
o \[:o] u006F_0308 o dieresis
u \[:u] u0075_0308 u dieresis
y \[:y] u0079_0308 y dieresis
A \[^A] u0041_0302 A circumflex
E \[^E] u0045_0302 E circumflex
I \[^I] u0049_0302 I circumflex
O \[^O] u004F_0302 O circumflex
U \[^U] u0055_0302 U circumflex
a \[^a] u0061_0302 a circumflex
e \[^e] u0065_0302 e circumflex
i \[^i] u0069_0302 i circumflex
o \[^o] u006F_0302 o circumflex
u \[^u] u0075_0302 u circumflex
A \[`A] u0041_0300 A grave
E \[`E] u0045_0300 E grave
I \[`I] u0049_0300 I grave
O \[`O] u004F_0300 O grave
U \[`U] u0055_0300 U grave
a \[`a] u0061_0300 a grave
e \[`e] u0065_0300 e grave
i \[`i] u0069_0300 i grave
o \[`o] u006F_0300 o grave
u \[`u] u0075_0300 u grave
A \[~A] u0041_0303 A tilde
N \[~N] u004E_0303 N tilde
O \[~O] u004F_0303 O tilde
a \[~a] u0061_0303 a tilde
n \[~n] u006E_0303 n tilde
o \[~o] u006F_0303 o tilde
\[vS] u0053_030C S caron
\[vs] u0073_030C s caron
\[vZ] u005A_030C Z caron
\[vz] u007A_030C z caron
C \[,C] u0043_0327 C cedilla
c \[,c] u0063_0327 c cedilla
A \[oA] u0041_030A A ring
a \[oa] u0061_030A a ring
Quotation marks
The neutral double quote, often useful when documenting programming
languages, is also available as a special character for convenient
embedding in macro arguments; see subsection "Fundamental character
set" above.
Output Input Unicode Notes
------------------------------------------------------------------------
,, \[Bq] u201E low double comma quote
, \[bq] u201A low single comma quote
" \[lq] u201C left double quote
" \[rq] u201D right double quote
` \[oq] u2018 single opening (left) quote
' \[cq] u2019 single closing (right) quote
' \[aq] u0027 apostrophe, neutral single quote
" " u0022 neutral double quote
" \[dq] u0022 neutral double quote
<< \[Fo] u00AB left double chevron
>> \[Fc] u00BB right double chevron
< \[fo] u2039 left single chevron
> \[fc] u203A right single chevron
Punctuation
The Unicode name for U+00B7 is "middle dot", which is unfortunately
confusable with the groff mnemonic for the visually similar but
semantically distinct multiplication dot; see subsection "Mathematical
symbols" below.
Output Input Unicode Notes
------------------------------------------------------------------------
! \[r!] u00A1 inverted exclamation mark
? \[r?] u00BF inverted question mark
. \[pc] u00B7 centered period
-- \[em] u2014 em-dash +
- \[en] u2013 en-dash
- \[hy] u2010 hyphen +
Brackets
On typesetting devices, the bracket extensions are font-invariant
glyphs; that is, they are rendered the same way regardless of font
(with a drawing escape sequence). On terminals, they are not font-
invariant; groff maps them rather arbitrarily to U+23AA ("curly bracket
extension"). In AT&T troff, only one glyph was available to vertically
extend brackets, braces, and parentheses: \(bv.
Not all devices supply bracket pieces that can be piled up with \b due
to the restrictions of the escape's piling algorithm. A general
solution to build brackets out of pieces is the following macro:
.\" Make a pile centered vertically 0.5em above the baseline.
.\" The first argument is placed at the top.
.\" The pile is returned in string 'pile'.
.eo
.de pile-make
. nr pile-wd 0
. nr pile-ht 0
. ds pile-args
.
. nr pile-# \n[.$]
. while \n[pile-#] \{\
. nr pile-wd (\n[pile-wd] >? \w'\$[\n[pile-#]]')
. nr pile-ht +(\n[rst] - \n[rsb])
. as pile-args \v'\n[rsb]u'\"
. as pile-args \Z'\$[\n[pile-#]]'\"
. as pile-args \v'-\n[rst]u'\"
. nr pile-# -1
. \}
.
. ds pile \v'(-0.5m + (\n[pile-ht]u / 2u))'\"
. as pile \*[pile-args]\"
. as pile \v'((\n[pile-ht]u / 2u) + 0.5m)'\"
. as pile \h'\n[pile-wd]u'\"
..
.ec
Another complication is the fact that some glyphs which represent
bracket pieces in AT&T troff can be used for other mathematical symbols
as well, for example \(lf and \(rf, which provide the floor operator.
Some output devices, such as dvi, don't unify such glyphs. For this
reason, the glyphs \[lf], \[rf], \[lc], and \[rc] are not unified with
similar-looking bracket pieces. In groff, only glyphs with long names
are guaranteed to pile up correctly for all devices--provided those
glyphs are available.
Output Input Unicode Notes
------------------------------------------------------------------------
[ [ u005B left square bracket
[ \[lB] u005B left square bracket
] ] u005D right square bracket
] \[rB] u005D right square bracket
{ { u007B left brace
{ \[lC] u007B left brace
} } u007D right brace
} \[rC] u007D right brace
< \[la] u27E8 left angle bracket
> \[ra] u27E9 right angle bracket
| \[bv] u23AA brace vertical extension + ***
| \[braceex] u23AA brace vertical extension
| \[bracketlefttp] u23A1 left square bracket top
| \[bracketleftex] u23A2 left square bracket extension
| \[bracketleftbt] u23A3 left square bracket bottom
| \[bracketrighttp] u23A4 right square bracket top
| \[bracketrightex] u23A5 right square bracket extension
| \[bracketrightbt] u23A6 right square bracket bottom
,- \[lt] u23A7 left brace top +
{ \[lk] u23A8 left brace middle +
`- \[lb] u23A9 left brace bottom +
,- \[bracelefttp] u23A7 left brace top
{ \[braceleftmid] u23A8 left brace middle
`- \[braceleftbt] u23A9 left brace bottom
| \[braceleftex] u23AA left brace extension
-. \[rt] u23AB right brace top +
} \[rk] u23AC right brace middle +
-' \[rb] u23AD right brace bottom +
-. \[bracerighttp] u23AB right brace top
} \[bracerightmid] u23AC right brace middle
-' \[bracerightbt] u23AD right brace bottom
| \[bracerightex] u23AA right brace extension
/ \[parenlefttp] u239B left parenthesis top
| \[parenleftex] u239C left parenthesis extension
\ \[parenleftbt] u239D left parenthesis bottom
\ \[parenrighttp] u239E right parenthesis top
| \[parenrightex] u239F right parenthesis extension
/ \[parenrightbt] u23A0 right parenthesis bottom
Arrows
Output Input Unicode Notes
------------------------------------------------------------------------
<- \[<-] u2190 horizontal arrow left +
-> \[->] u2192 horizontal arrow right +
<-> \[<>] u2194 bidirectional horizontal arrow
v \[da] u2193 vertical arrow down +
^ \[ua] u2191 vertical arrow up +
^v \[va] u2195 bidirectional vertical arrow
<= \[lA] u21D0 horizontal double arrow left
=> \[rA] u21D2 horizontal double arrow right
<=> \[hA] u21D4 bidirectional horizontal double arrow
v \[dA] u21D3 vertical double arrow down
^ \[uA] u21D1 vertical double arrow up
^=v \[vA] u21D5 bidirectional vertical double arrow
- \[an] u23AF horizontal arrow extension
Rules and lines
On typesetting devices, the font-invariant glyphs (see subsection
"Brackets" above) \[br], \[ul], and \[rn] form corners when adjacent;
they can be used to build boxes. On terminal devices, they are mapped
as shown in the table. The Unicode-derived names of these three glyphs
are approximations.
The input character _ always accesses the underscore glyph in a font;
\[ul], by contrast, may be font-invariant on typesetting devices.
The baseline rule \[ru] is a font-invariant glyph, namely a rule of
one-half em.
In AT&T troff, \[rn] also served as a one en extension of the square
root symbol. groff favors \[radicalex] for this purpose; see
subsection "Mathematical symbols" below.
Output Input Unicode Notes
------------------------------------------------------------------------
| | u007C bar
| \[ba] u007C bar
| \[br] u2502 box rule +
_ _ u005F underscore, low line +
_ \[ul] --- underrule +
- \[rn] u203E overline +
_ \[ru] --- baseline rule +
| \[bb] u00A6 broken bar
/ / u002F slash, solidus +
/ \[sl] u002F slash, solidus +
\ \[rs] u005C reverse solidus
Text markers
Output Input Unicode Notes
------------------------------------------------------------------------
O \[ci] u25CB circle +
o \[bu] u2022 bullet +
<*> \[dg] u2020 dagger +
<**> \[dd] u2021 double dagger +
<> \[lz] u25CA lozenge, diamond
[] \[sq] u25A1 square +
<paragraph> \[ps] u00B6 pilcrow sign
<section> \[sc] u00A7 section sign +
<= \[lh] u261C hand pointing left +
=> \[rh] u261E hand pointing right +
@ @ u0040 at sign
@ \[at] u0040 at sign
# # u0023 number sign
# \[sh] u0023 number sign
<cr> \[CR] u21B5 carriage return
\/ \[OK] u2713 check mark
Legal symbols
The Bell System logo is not supported in groff.
Output Input Unicode Notes
------------------------------------------------------------------------
(C) \[co] u00A9 copyright sign +
(R) \[rg] u00AE registered sign +
tm \[tm] u2122 trade mark sign
\[bs] --- Bell System logo +
Currency symbols
Output Input Unicode Notes
------------------------------------------------------------------------
$ $ u0024 dollar sign
$ \[Do] u0024 dollar sign
c \[ct] u00A2 cent sign +
EUR \[eu] u20AC Euro sign
EUR \[Eu] u20AC variant Euro sign
Y \[Ye] u00A5 yen sign
L \[Po] u00A3 pound sign
x \[Cs] u00A4 currency sign
Units
Output Input Unicode Notes
------------------------------------------------------------------------
<degree> \[de] u00B0 degree sign +
<permille> \[%0] u2030 per thousand, per mille sign
' \[fm] u2032 arc minute sign, foot mark +
'' \[sd] u2033 arc second sign
<micro> \[mc] u00B5 micro sign
a \[Of] u00AA feminine ordinal indicator
o \[Om] u00BA masculine ordinal indicator
Logical symbols
The variants of the not sign may differ in appearance or spacing
depending on the device and font selected. Unicode does not encode a
discrete "bitwise or" sign: on typesetting devices, it is drawn shorter
than the bar, about the same height as a capital letter. Terminal
devices unify \[ba] and \[or].
Output Input Unicode Notes
------------------------------------------------------------------------
^ \[AN] u2227 logical and
v \[OR] u2228 logical or
~ \[no] u00AC logical not + ***
~ \[tno] u00AC text variant of \[no]
<there exists> \[te] u2203 there exists
<for all> \[fa] u2200 for all
<such that> \[st] u220B such that
<therefore> \[3d] u2234 therefore
<therefore> \[tf] u2234 therefore
| | u007C bar
| \[or] u007C bitwise or +
Mathematical symbols
\[Fn] also appears in subsection "Supplementary Latin letters" above.
Observe the two varieties of the plus-minus, multiplication, and
division signs; \[+-], \[mu], and \[di] are normally drawn from the
special font, but have text font variants. Also be aware of three
glyphs available in special font variants that are normally drawn from
text fonts: the plus, minus, and equals signs. These variants may
differ in appearance or spacing depending on the device and font
selected.
In AT&T troff, \(rn ("root en extender") served as the horizontal
extension of the radical (square root) sign, \(sr, and was drawn at the
maximum height of the typeface's bounding box; this enabled the special
character to double as an overline (see subsection "Rules and lines"
above). A contemporary font's radical sign might not ascend to such an
extreme. In groff, you can instead use \[radicalex] to continue the
radical sign \[sr]; these special characters are intended for use with
text fonts. \[sqrt] and \[sqrtex] are their counterparts with
mathematical spacing.
Output Input Unicode Notes
------------------------------------------------------------------------
1/2 \[12] u00BD one half symbol +
1/4 \[14] u00BC one quarter symbol +
3/4 \[34] u00BE three quarters symbol
+
1/8 \[18] u215B one eighth symbol
3/8 \[38] u215C three eighths symbol
5/8 \[58] u215D five eighths symbol
7/8 \[78] u215E seven eighths symbol
^1 \[S1] u00B9 superscript one
^2 \[S2] u00B2 superscript two
^3 \[S3] u00B3 superscript three
+ + u002B plus
+ \[pl] u002B special variant of
plus + ***
- \[-] u002D minus
- \[mi] u2212 special variant of
minus + ***
-+ \[-+] u2213 minus-plus
+- \[+-] u00B1 plus-minus + ***
+- \[t+-] u00B1 text variant of \[+-]
. \[md] u22C5 multiplication dot
x \[mu] u00D7 multiplication sign +
***
x \[tmu] u00D7 text variant of \[mu]
x \[c*] u2297 circled times
+ \[c+] u2295 circled plus
/ \[di] u00F7 division sign + ***
/ \[tdi] u00F7 text variant of \[di]
/ \[f/] u2044 fraction slash
* * u002A asterisk
* \[**] u2217 mathematical asterisk
+
<= \[<=] u2264 less than or equal to
+
>= \[>=] u2265 greater than or equal
to +
<< \[<<] u226A much less than
>> \[>>] u226B much greater than
= = u003D equals
= \[eq] u003D special variant of
equals + ***
!= \[!=] u003D_0338 not equals +
== \[==] u2261 equivalent +
!== \[ne] u2261_0338 not equivalent
=~ \[=~] u2245 approximately equal
to
-~ \[|=] u2243 asymptotically equal
to +
~ \[ti] u007E tilde +
~ \[ap] u223C similar to, tilde
operator +
~~ \[~~] u2248 almost equal to
~= \[~=] u2248 almost equal to
<proportional to> \[pt] u221D proportional to +
{} \[es] u2205 empty set +
<element of> \[mo] u2208 element of a set +
<not element of> \[nm] u2208_0338 not element of set
<proper subset> \[sb] u2282 proper subset +
<not subset> \[nb] u2282_0338 not subset
<proper superset> \[sp] u2283 proper superset +
<not superset> \[nc] u2283_0338 not superset
<subset or equal> \[ib] u2286 subset or equal +
<superset or equal> \[ip] u2287 superset or equal +
<intersection> \[ca] u2229 intersection, cap +
<union> \[cu] u222A union, cup +
<angle> \[/_] u2220 angle
<perpendicular> \[pp] u22A5 perpendicular
<integral> \[is] u222B integral +
<integral> \[integral] u222B integral ***
<sum> \[sum] u2211 summation ***
<product> \[product] u220F product ***
<coproduct> \[coproduct] u2210 coproduct ***
<nabla> \[gr] u2207 gradient +
<sqrt> \[sr] u221A radical sign, square
root +
- \[rn] u203E overline +
\[radicalex] --- radical extension
<sqrt> \[sqrt] u221A radical sign, square
root ***
\[sqrtex] --- radical extension ***
|~ \[lc] u2308 left ceiling +
~| \[rc] u2309 right ceiling +
|_ \[lf] u230A left floor +
_| \[rf] u230B right floor +
<infinity> \[if] u221E infinity +
<Aleph> \[Ah] u2135 aleph symbol
f \[Fn] u0192 lowercase f with
hook, function
<Im> \[Im] u2111 blackletter I,
imaginary part
<Re> \[Re] u211C blackletter R, real
part
p \[wp] u2118 Weierstrass p
<del> \[pd] u2202 partial differential
/h \[-h] u210F h bar
/h \[hbar] u210F h bar
Greek glyphs
These glyphs are intended for technical use, not for typesetting Greek
language text; normally, the uppercase letters have upright shape, and
the lowercase ones are slanted.
Output Input Unicode Notes
------------------------------------------------------------------------
A \[*A] u0391 uppercase alpha +
B \[*B] u0392 uppercase beta +
<Gamma> \[*G] u0393 uppercase gamma +
<Delta> \[*D] u0394 uppercase delta +
E \[*E] u0395 uppercase epsilon +
Z \[*Z] u0396 uppercase zeta +
H \[*Y] u0397 uppercase eta +
<Theta> \[*H] u0398 uppercase theta +
I \[*I] u0399 uppercase iota +
K \[*K] u039A uppercase kappa +
<Lambda> \[*L] u039B uppercase lambda +
M \[*M] u039C uppercase mu +
N \[*N] u039D uppercase nu +
<Xi> \[*C] u039E uppercase xi +
O \[*O] u039F uppercase omicron +
<Pi> \[*P] u03A0 uppercase pi +
P \[*R] u03A1 uppercase rho +
<Sigma> \[*S] u03A3 uppercase sigma +
T \[*T] u03A4 uppercase tau +
Y \[*U] u03A5 uppercase upsilon +
<Phi> \[*F] u03A6 uppercase phi +
X \[*X] u03A7 uppercase chi +
<Psi> \[*Q] u03A8 uppercase psi +
<Omega> \[*W] u03A9 uppercase omega +
<alpha> \[*a] u03B1 lowercase alpha +
<beta> \[*b] u03B2 lowercase beta +
<gamma> \[*g] u03B3 lowercase gamma +
<delta> \[*d] u03B4 lowercase delta +
<epsilon> \[*e] u03B5 lowercase epsilon +
<zeta> \[*z] u03B6 lowercase zeta +
<eta> \[*y] u03B7 lowercase eta +
<theta> \[*h] u03B8 lowercase theta +
<iota> \[*i] u03B9 lowercase iota +
<kappa> \[*k] u03BA lowercase kappa +
<lambda> \[*l] u03BB lowercase lambda +
<mu> \[*m] u03BC lowercase mu +
<nu> \[*n] u03BD lowercase nu +
<xi> \[*c] u03BE lowercase xi +
o \[*o] u03BF lowercase omicron +
<pi> \[*p] u03C0 lowercase pi +
<rho> \[*r] u03C1 lowercase rho +
<sigma> \[*s] u03C3 lowercase sigma +
<tau> \[*t] u03C4 lowercase tau +
<upsilon> \[*u] u03C5 lowercase upsilon +
<phi> \[*f] u03D5 lowercase phi +
<chi> \[*x] u03C7 lowercase chi +
<psi> \[*q] u03C8 lowercase psi +
<omega> \[*w] u03C9 lowercase omega +
<epsilon> \[+e] u03F5 variant epsilon (lunate)
<theta> \[+h] u03D1 variant theta (cursive form)
<pi> \[+p] u03D6 variant pi (similar to omega)
<phi> \[+f] u03C6 variant phi (curly shape)
<sigma> \[ts] u03C2 terminal lowercase sigma +
Playing card symbols
Output Input Unicode Notes
------------------------------------------------------------------------
C \[CL] u2663 solid club suit
S \[SP] u2660 solid spade suit
H \[HE] u2665 solid heart suit
D \[DI] u2666 solid diamond suit
History
A consideration of the typefaces originally available to AT&T nroff and
troff illuminates many conventions that one might regard as
idiosyncratic fifty years afterward. (See section "History" of roff(7)
for more context.) The face used by the Teletype Model 37 terminals of
the Murray Hill Unix Room was based on ASCII, but assigned multiple
meanings to several code points, as suggested by that standard.
Decimal 34 (") served as a dieresis accent and neutral double quotation
mark; decimal 39 (') as an acute accent, apostrophe, and closing
(right) single quotation mark; decimal 45 (-) as a hyphen and a minus
sign; decimal 94 (^) as a circumflex accent and caret; decimal 96 (`)
as a grave accent and opening (left) single quotation mark; and decimal
126 (~) as a tilde accent and (with a half-line motion) swung dash.
The Model 37 bore an optional extended character set offering upright
Greek letters and several mathematical symbols; these were documented
as early as the kbd(VII) man page of the (First Edition) Unix
Programmer's Manual.
At the time Graphic Systems delivered the C/A/T phototypesetter to
AT&T, the ASCII character set was not considered a standard basis for a
glyph repertoire by traditional typographers. In the stock Times
roman, italic, and bold styles available, several ASCII characters were
not present at all, nor was most of the Teletype's extended character
set. AT&T commissioned a "special" font to ensure no loss of
repertoire.
A representation of the coverage of the C/A/T's text fonts follows.
The glyph resembling an underscore is a baseline rule, and that
resembling a vertical line is a box rule. In italics, the box rule was
not slanted. We also observe that the hyphen and minus sign were
already "de-unified" by the fonts provided; a decision whither to map
an input "-" therefore had to be taken.
+-----------------------------------------------------+
|A B C D E F G H I J K L M N O P Q R S T U V W X Y Z |
|a b c d e f g h i j k l m n o p q r s t u v w x y z |
|0 1 2 3 4 5 6 7 8 9 fi fl ffi ffl |
|! $ % & ( ) ` ' * + - . , / : ; = ? [ ] | |
|o [] -- - _ 1/4 1/2 3/4 <degree> <*> ' c (R) (C) |
+-----------------------------------------------------+
The special font supplied the missing ASCII and Teletype extended
glyphs, among several others. The plus, minus, and equals signs
appeared in the special font despite availability in text fonts "to
insulate the appearance of equations from the choice of standard [read:
text] fonts"--a priority since troff was turned to the task of
mathematical typesetting as soon as it was developed.
We note that AT&T took the opportunity to de-unify the apostrophe/right
single quotation mark from the acute accent (a choice ISO later
duplicated in its 8859 series of standards). A slash intended to be
mirror-symmetric with the backslash was also included, as was the Bell
System logo; we do not attempt to depict the latter.
+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
|<alpha> <beta> <gamma> <delta> <epsilon> <zeta> <eta> <theta> <iota> <kappa> <lambda> <mu> <nu> <xi> o <pi> <rho> <sigma> <sigma> <tau> <upsilon> <phi> <chi> <psi> <omega> |
|<Gamma> <Delta> <Theta> <Lambda> <Xi> <Pi> <Sigma> Y <Phi> <Psi> <Omega> |
|" ' \ ^ _ ` ~ / < > { } # @ + - = * |
|>= <= == ~= ~ != ^ v <- -> x / +- ~ {} |
|<section> <**> <= => | O ,- `- -. -' { } | |_ _| |~ ~| |
+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
One ASCII character as rendered by the Model 37 was apparently
abandoned. That device printed decimal 124 (|) as a broken vertical
line, like Unicode U+00A6 (|). No equivalent was available on the
C/A/T; the box rule \[br], brace vertical extension \[bv], and "or"
operator \[or] were used as contextually appropriate.
Devices supported by AT&T device-independent troff exhibited some
differences in glyph detail. For example, on the Autologic APS-5
phototypesetter, the square \(sq became filled in the Times bold face.
Files
The files below are loaded automatically by the default troffrc.
/opt/local/share/groff/1.23.0/tmac/composite.tmac
assigns alternate mappings for identifiers after the first in a
composite special character escape sequence. See subsection
"Accents" above.
/opt/local/share/groff/1.23.0/tmac/fallbacks.tmac
defines fallback mappings for Unicode code points such as the
increment sign (U+2206) and upper- and lowercase Roman numerals.
Authors
This document was written by James Clark <jjc@jclark.com>, with
additions by Werner Lemberg <wl@gnu.org> and Bernd Warken <groff-bernd
.warken-72@web.de>, revised to use tbl(1) by Eric S. Raymond <esr@
thyrsus.com>, and largely rewritten by G. Branden Robinson <g.branden
.robinson@gmail.com>.
See also
Groff: The GNU Implementation of troff, by Trent A. Fisher and Werner
Lemberg, is the primary groff manual. Section "Using Symbols" may be
of particular note. You can browse it interactively with "info
'(groff) Using Symbols'".
"An extension to the troff character set for Europe", E.G. Keizer, K.J.
Simonsen, J. Akkerhuis; EUUG Newsletter, Volume 9, No. 2, Summer 1989
The Unicode Standard <http://www.unicode.org>
"7-bit Character Sets" <https://www.aivosto.com/articles/charsets-7bit
.html> by Tuomas Salste documents the inherent ambiguity and
configurable code points of the ASCII encoding standard.
"Nroff/Troff User's Manual" by Joseph F. Ossanna, 1976, AT&T Bell
Laboratories Computing Science Technical Report No. 54, features two
tables that throw light on the glyph repertoire available to
"typesetter roff" when it was first written. Be careful of re-typeset
versions of this document that can be found on the Internet. Some do
not accurately represent the original document: several glyphs are
obviously missing. More subtly, lowercase Greek letters are rendered
upright, not slanted as they appeared in the C/A/T's special font and
as expected by troff users.
groff_rfc1345(7) describes an alternative set of special character
glyph names, which extends and in some cases overrides the definitions
listed above.
groff(1), troff(1), groff(7)
groff 1.23.0 2 July 2023 groff_char(7)
groff 1.23.0 - Generated Fri Dec 22 13:27:49 CST 2023